Semiconductor packages have been continuously improved to meet new demands for high-performance, small-size and high-speed electronic appliances. Accordingly, semiconductor packages have been evolved from old-fashioned dual in-line packages (DIPs) to state-of-the-art semiconductor packages such as CSPs. As a result, electronic appliances such as smart phones and tablet computers can be miniaturized using the CSPs as their components.
The CSPs are particularly ideal or suitable for ideal for a package having a large number of pins (e.g., 100+) with high speed operation or for a package having a relatively large size chip. Although the definition of the CSPs has not been fixed in semiconductor industry, the packages that are smaller than about 120% of the size of a semiconductor chip are typically referred to as a CSP. Even semiconductor packages larger than 120% of the size of a chip, such as ball grid array (BGA) packages, land grid array (LGA) packages, and small outline non-leaded (SON) packages, may be considered to be a CSP. In particular, the BGA packages having solder balls instead of leads mounted on the lower surface thereof, the LGA packages having a land array mounted on the lower surface thereof, and the SON packages having two land arrays instead of leads mounted on the lower surface thereof are examples of the CSPs.
In a package such as a flip chip Chip Scale Package (fcCSP), an integrated circuit (IC) may be mounted to a substrate (e.g., a printed circuit board (PCB) or other integrated circuit carrier) through a bump on trace (BOT) interconnection.
In light of the demand for ever smaller packages, attempts are often made to reduce the distance between adjacent bumps, which is known as the bump pitch. One way to reduce the bump pitch is by shrinking the width of the metal traces used in the BOT interconnection. Unfortunately, reducing the width of the metal traces may lead to undesirable or detrimental consequences.
Corresponding numerals and symbols in the different figures generally refer to corresponding parts unless otherwise indicated. The figures are drawn to clearly illustrate the relevant aspects of the embodiments and are not necessarily drawn to scale.